The ZCI barrel is the best value for performance barrel on the airsoft market. This is a great option for Airsofters looking for a high-quality steel barrel at a low price. This affordable barrel paired with an rhop, makes it one of the best performing barrels on the market. ZCI has one of the best prices for performance ratios, being able to give a good performance for an affordable price. ZCI Barrels are constructed out of stainless steel and also feature a quality bore surface quality, very good for the price. ZCI Barrels are manufactured in China, which helps to bring costs and prices of ZCI Barrels down. The machining method used for ZCI barrels is Barrel Extrusion, a common method used for most inner barrels for airsoft. The machining tolerance is around +0.02mm - 0.05mm. In conclusion, ZCI stainless steel barrels is the best stainless-steel barrel and absolutely recommended by airsoft technicians around the world.